Electrolytic diaphragm



Dec. y6, 1932,

w. H. Woot` ELECTROLYTIC DIAPHRAGM Filed June 23. 1927 M. H m

Inventor @JM wf v .Atbornegs Patented Dec. s, 1932 UNITED STATES i WILLIAM H. woon, oF soU'ria EUCLID, omo

nLEcTRoLYrIc DIAPHRAGM Application 4tiled .Tune 23,

This invention relates to the porous diaphragms employed in certain electrolytical operations to separate different liquids or electrodes from each other'while permitting the ready migration of ions, and the particular device to which my invention is chiefly directed is known in the art as a storage battery separator although many features of my invention are susceptible of wider use. It is important in devices of this nature that the porosity behigh, the texture uniform, pinholes and other openings being avoided, and a substantial amount of physical strength exhibited together with at least a substantial '15 degree of resistance to the chemical action of the electrolyte. Separatorsmade solely of simple substances like cloth, wood, earthenware, erforated insulation and the like have been ound unsatisfactory for various reasons which have resulted in attempts to make separators of a complex construction, employing a frame of some kind of supporting and strengthening material such for example as vulcanized rubber, having wicksor capillary inclusions supported therein. The objects of the present invention is the rovision of a new, simplied, and improve process whereby the manufacture of such composite se arators or diaphragrns is facilitated, and w ereb an increased portion .of the fibers or wie -forming materials are run transversely of the separator from one face to the other thereof, and whereby those wicks or capillaries are arranged in substantially uniform and regular manner over the surface of the same.y

In the drawing accompanying and forming a part of my application I have illustrated in a diagrammatic way a series of steps constituting Va part of my improved process of producing such separators together with a specimen separator produced thereby. It will be understood that several of the actual steps are not susceptible of ready illustration, so that no attempt is made to illustrate all the manipulations and procedures, but only to portray sufficient to enable those skilled in the art tov form successfully the invention in question; and` that certain 0 of the steps I have actually shown can be 1927. Serial No. 200,866.

eliminated `ormodified without departure from the scope of my invention.

Fig. l is a vertical longitudinal section of a mixing and rolling apparatus and illustrates steps of mixing and rolling which cons titute a part of my invention; Fig. 2 is a perspective view of a small section of the sheet produced thereby; Fig. 3 is a magnified view of a small portion of said sheet; Fig. 4 is a top plan View of another rolling machine 6 illustrating an optional processfor increasing the regularity of location of the Wicks or fibers Fig. 5 is a perspective view of a section of the sheet produced thereby; Fig. 6 is a magnified View of a `small section of that sheet; Fig. 7 is a perspective view of a block illustrating the mode of combining together a plurality of the before-mentioned sheets and subsequently severing the same to form separators; Fig. 8 is a perspective view of 70 one of the complete separators so made; and Fig. 9 is an enlarged microscopic view of a portion of said separator.v i

The matrix material which I employ is hereafter referred to as rubber, but by that term I do not limit myself strictly to the sap of the so-called rubber tree, but intend to include other substances having the hereinessential properties of rubber, namely elasticity, vulcanizability, resistance to eleetrolyte-corrosion, and high resistance to electric currents. As a wick-forming or capillary material I preferably employorganized keratin in librous form as set forth in m Patents Nos. 1,405,703 and 1,502,455, pre 8 erably in the form of mammalian-hair from which the scales havev been loosened or removed by appropriate chemical treatment, as by the action of lime or sodium sulfite. However, it is equally within the purview of the present invention to employ untreated hair, or birds-feathers, cotton, hemp or other pervious cellulose strands, iax, disintegrated plant stems, or other capillary substance which occurs in fibrous form, the choice being determined partly by financial considerations and partly by the chemical nature of the electrolyte.v

The fibrous material is preferably chopped into such lengths as can be readily mixed 1 in-Fig. 1.l from which it passes in a regullated manner, the item of regulation being here implied by the auger screw feed 2, through an extruding nozzle 3 which delivers the mass in the form of a ribbon to a series of rolls 4,' 5, 6, 7, 8, be the same more or less in number, by which the material is reduced to the form ofa thin, elongated sheet 10. It is desirable that the length of at `least the greater part of these fibrous materials' be greater than the thickness of the sheet, and necessary that it be glreater than the thickness of the-separator w ich is to be made and I preferably employ about the largest amount of such fibrous material as will produce a homogeneous and bubble-free v mixture in combination with the matrix substandard rubber mac ines and processes,

- the proper materials,

stance. Inasmuch as the permissible limits of composition are extremely wide I do not deem it necessary to afford any strict proportions, although an example of a possible proportion is three parts by weight of rubber to one part by weight of fibrous material. The larger the proportion of fiber, the larger the porosity of the resulting separator, while the the large the proportion of rubber the greater is the strength of .the same. The choice of composition necessarily rests upon the use to which the device is to be put. It will be found that the mixture thus 'madeis an extremely sticky and unpleasantmaterial to handle, but is entirel within the ability ofJ 1 the rollers are made of maintained-at proper temperatures, and applied with proper dusting and anti-sticking substances.l

. A cut of the'sheet 10 is shown at Fig. 2, anda small ortion taken from the point 11 thereof is s own under the microscope in Fig. 3, where it will be seen that the fibers 12 run somewhat criss-cross but always within the plane of the-sheet and prevailingly in one direction due to the rolling process.

It is possible with perfectly satisfactory being assumed that h results to jump from this oint immediatel to the step illustrated in Fig. 7 but it is pre erable for certain uses at this point to interpose a further step designed to bring the fibrous materlal more nearlyparallel to a given direction, and thereby increase the orosity of the separator for a given stiffness.

o do this I pass the sheet 10 through a further series of rolls illustrated in Fig. 4 which are preferably arranged directly in sequence eHect of the smooth surfaced rolls is to atf ten the surface of the sheet without at the ,same time restoring the irregular arrangement of the fibers', with the result that most of the fibers ultimatelybecome arranged lengthwise ofthe sheet while still remaining wholly within the top` and bottom surface thereof.

The sheet produced as above -described is" severed into rectangular segments 10 or 17 as 'the case may be which are laid one upon the other as shown in Fig. 7 until a pile 18 is produced having the cross sectional shape and size of the separator or other diaphragm desired, and the whole vulcanized. Care is exercised that the surfaces of the sheets are sufficiently clean` to insure their adhering to-J gether into a unitary mass, afterwhich slices are removed from said pile transverse to the planes of. said sheets as shown at 19 in Fig. 7. In case of any predominant location of the fibers in a given direction as shown in Figs. 5 and v6 the sheets are so laid as to maintain such direction uniformi-n all the sheets, and the plane of slicing is transverse to that direction so that the majority of those fibers .traverse the resulting separator fromv side'to side.

In some cases the mere act of rolling illustrated in Fig. 1 produces a predominant lengthwise trend of the fibrous material so that the particular step illustrated in Fig. 4 for emphasizing the lengthwise arrangement is not necessary. Indeed it will be seen that the lnere act of' producing a sheet which-is thinner than the length of the majority of the fibers exercises a degree of selection y preventing a lvertical position of said fibers an increases the proportion of fibers which traverse the resulting separator from side to side even though no other selective action existed. Themere action of rolling lengthwise, particularly by successive steps with the consequent gradual increase of speed (since it is obvious that than the rolls 4 to transmit agiven weight of material per unit of time) necessarily helps 1;20

of strands by the use of corrugatto arrange the `fibers lengthwise. The further production ed rolls carries the selection slightly further.

the rolls 8 must rotate faster It is immaterial so. far as concerns my 1n- I what can be done, and I do not limit myself except as recited in my several claims which I deslre may be construed each indgpendently of limitations contained in other Having thus described my invention what lo Iclaim is:

' 1. The process of making a porous diaphragm for electrolyticuse which contains the ste s of mixing indiscriminatel together a plastic matrix substance and a fi rous pervious substance, rolling such mixture repeaty edly in the same direction, superposing the sheets thereby produced to form a pile 'with theY grain of the majority of said sheets arallel, causing said sheets to adhere toge er, and slicing such pile transverselyl of Athe gram. A p i 2. The process of making a porousdiahragm for electrolytic use which contains t e stepsf mixing intimately together a plastic matrix substance and a fibrous rvious substance, forming said mixture into sheets, forming said sheets alternately into corrugated form and smooth form until the fibers are arranged prevailingly in one direction, collecting the sheets into a pile, hardening said (pile, and slicing said pile transverse- 1y of sai sheets and of the prevailing direction of said fibers. In testimony whereof I hereunto ax my signature.

WILLIAM H. s WOOD. 

